(CNN) -- More than 30 hours of incessant rain eased Thursday on Australia's east coast, where widespread flooding cut off thousands of people from services and resulted in four areas being declared disaster zones, officials said.

"A lot of those rivers are receding, which is good news," said David Webber, a state emergency services spokesman for New South Wales. Nearly 4,000 people remained isolated Thursday morning, he said.

"The entire region has been drenched by phenomenal amounts of rain," said Steve Whan, the emergency services minister, in a written statement.

The disaster areas cover Coffs Harbour, a coastal town subject to flash flooding by Coffs Creek, Nambucca and Bellingen. On Wednesday, after visiting New South Wales' north coast to assess the flood damage, particularly to roads, Whan said he added Clarence Valley to the list.

He said Coffs Harbour recorded up to 440 mm (17.3 inches) in 24 hours and Nambucca got pounded by 700 mm (27.6 inches) in 48 hours.

The disaster declarations make the areas eligible to receive government funding to aid their recovery.

"About 3,870 residents in Kalang Valley ... Thora and Darkwood ... and parts of Bellingen ... have been isolated since Tuesday night and are likely to be cut off until at least Thursday night in Bellingen and possibly the weekend upstream," Whan said.

More than 160 businesses were affected by floodwaters in Coffs Harbour, and authorities received reports of garbage bins, animal carcasses and drums washing up on beaches, he said.

About 500 people spent Wednesday night in evacuation centers in Coffs Harbour and another 250 overnighted in evacuation centers in the area of Urunga, which is on the Bellinger River, Webber said. No fatalities were reported, he said.

Coffs Harbour is about 435 km (270 miles) north of Sydney.

Across New South Wales, emergency workers and some 900 volunteers received 1,070 requests for help, 70 percent of which they had responded to by dawn Thursday, Webber said. Most of the calls were about minor damage, flooding, leaking roofs, and fallen trees and branches, Webber said.

But about 100 of them -- primarily from the area of Coffs Harbour -- were requests for rescue by ambulance crews, he said.

Webber credited the residents with being able, for the most part, to fend for themselves. Since coastal flooding occurs regularly, "most people in those areas are quite prepared," he said.

The last such flood in Coffs Harbour occurred in 1996, when it resulted in one death and was described as a 100-year event. This latest inundation of 5.14 meters (16.9 feet) over flood stage is 0.26 meters (10.2 inches) above the mark hit 13 years ago.